1. Field of the Invention
The present invention relates to an oxidation method for a semiconductor process, which thermally oxidizes the surface of a target substrate by water vapor. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or a glass substrate used for an LCD (Liquid Crystal Display) or FPD (Flat Panel Display), by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
2. Description of the Related Art
In manufacturing semiconductor integrated circuits, a semiconductor substrate, such as a silicon wafer, is subjected to various processes, such as film-formation, etching, oxidation, diffusion, and reformation, in general. For example, oxidation includes oxidation of the surface of a mono-crystalline silicon film, and oxidation of a metal film. Particularly, a silicon oxide film formed by oxidation is applied to a device isolation film, gate oxide film, capacitor insulating film, or the like.
A vacuum oxidation method for forming a thin film under a vacuum pressure is disclosed, for example, in Jpn. Pat. Appln. KOKAI Publication No. 57-1232 (patent publication 1), in which H2 and O2 are supplied into a vacuum furnace to perform hydrogen burning oxidation. Further, a wet oxidation method is disclosed, for example, in Jpn. Pat. Appln. KOKAI Publication No. 3-140453 (patent publication 2), in which hydrogen and oxygen are burned within an external combustion apparatus using plasma to generate water vapor, which is then used for oxidation.
Another wet oxidation method is disclosed, for example, in Jpn. Pat. Appln. KOKAI Publication No. 11-330468 (patent publication 3), in which hydrogen and oxygen are made to react with each other by a catalyst at a low temperature to generate water vapor, which is then supplied into a vacuum furnace. Furthermore, another oxidation method is disclosed, for example, in Jpn. Pat. Appln. KOHYO Publication No. 2001-527279 (patent publication 4) and Jpn. Pat. Appln. KOKAI Publication No. 2002-176052 (patent publication 5), in which hydrogen and oxygen are supplied into a vacuum furnace to generate activated species, which are used for oxidation.